Process using transition metal complexes for the separation of dioxygen from a gas mixture by electrodecomplexation

A process for separating dioxygen from a gaseous mixture containing dioxygen, which comprises:

• a) absorbing dioxygen by one or more transition metal complexes at a low oxidation state of the formula (A):
• (L.sub.n (M.sup.+p).sub.m (X.sup.-z).sub.x.sup.mp-xz (A)
• wherein L represents a coordinate site which is a part of one or more ligands selected from the group consisting of phosphines, phosphine oxides and phosphites;
• each of which stabilizes low valences of M;
• wherein M is a transition metal which binds O.sub.2 thereby forming a peroxo dihapto deoxygenated species of the formula:
• ##STR8## and selected from the group consisting of Pd, Pt, Rh, Ni, Ir and Mo;
• X is a coordinating anion;
• n is an integer of from 2 to 12, and represents the number of coordination sites L,
• p represents the oxidation state number of M in the complex of the formula (A),
• m is an integer of 1 or 2, and represents the number of metal centers of the complex,
• z is an integer of from 1 to 3, and represents the charge of the X.sup.-z anion,
• x ranges from 0 to 4, and represents the number of anions X identical or different, coordinated to the metal centers M,
• said absorption causing formation of a peroxo dihapto deoxygenated complex of the formula (B):
• (L.sub.n '(M.sup.p+2 O.sub.2).sub.m' (X.sup.-z).sub.x).sup.m'p-x'-z(B)
• in which L, M, X, p, z have the same meanings as above,
• n', m', x' have, respectively, the same meanings as n, m and x with
• .ltoreq. n'.ltoreq.n,
• 1.ltoreq.m'.ltoreq.m, and
• 0.ltoreq.x'.ltoreq.x;
• b) desorbing dioxygen from the complex by electrochemically oxidizing the peroxo dihapto product complex (B) obtained by reaction of the complex of formula (A) with O.sub.2 ;
• and
• c) recovering desorbed oxygen.